Topical composition with skin lightening effect

ABSTRACT

A topical cosmetic composition for increasing skin whitening or lightening is described. The composition includes a pomegranate extract in an amount effective to reduce melanin composition. The pomegranate extract may be standardized to about 20% punicalagin. The composition may also include an extract from the genus  larix , such as  Larix sibirica . The  larix sibirica  may be standardized to 80% taxifolin. A method for using the compositions is described.

BACKGROUND

The present invention relates to topical compositions to provide skinwhitening or lightening effect.

Skin color is primarily determined by the amount of melanin in the skin.Melanin is a brown-black pigment present in the skin. Due to the darkcolor of the pigment, lower amounts of melanin result in lighter skincolor while higher amounts result in darker skin color. Melanin isformed by the oxidation of the amino acid tyrosine todihydroxyphenalanine in melanocytes. This reaction is catalyzed by theenzyme tyrosinase.

Excessive skin pigmentation may be caused by hormone abnormality in thehuman body, genetic diseases, etc., regardless of UV, or by excessivemelanogenesis and melanin maldistribution due to excessive UVirradiation. A suitable amount of melanin in the skin has the positiveeffect of maintaining the skin healthy and absorbing UV, etc. However,excessive melanin results in negative effects, such as skin darkeningand non-uniform skin color. Thus, many scientists have studiedmelanogenesis inhibition.

As a result of this pivotal role of tyrosinase in melanin formation,efforts to develop effective skin whitening compositions have focused onagents that inhibit the function and activity of tyrosinase. Forexample, compositions have been proposed that include a variety of knowntyrosinase inhibitors, such as hydroquinone, vitamin C and itsderivatives, kojic acid, arbutin, glutathione, cysteine, and mulberryextract, among others.

A problem with synthetic skin lighteners such as hydroquinone or kojicacid is that they may cause skin irritation or acute dermatitis. Thus,there is a continuing desire to incorporate natural sources intocompositions in an attempt to address some of the undesirable aspects ofsynthetic products.

BRIEF SUMMARY

The present invention addresses some of the above issues. In one aspectof the invention, a topical composition is provided for reducing orinhibiting melanin production and it includes an effective amount ofpomegranate extract. The composition can be used to whiten or lightenthe skin. The pomegranate extract may be standardized to about 20%punicalagin.

Another aspect of the invention includes a topical composition thatcontains the combination of a pomegranate extract and an extract derivedfrom the plant genus Larix, for example larix sibirica (Siberian larch)to reduce or inhibit melanin product resulting in skin whitening orlightening. In one aspect, the pomegranate extract is standardized toabout 20% punicalagin and the larix extract is standardized to about 80%taxifolin. It has been found that surprisingly and unexpectedly thecombination synergistically reduces or inhibits melanin production.

The present invention also relates to a method for whitening skin thatincludes applying to the skin compositions according to the presentinvention in an amount and for a period of time sufficient to whiten theskin.

It is to be understood that this invention is not limited to theparticular compositions, methodology, or protocols described herein.Further, unless defined otherwise, all technical and scientific termsused herein have the same meaning as commonly understood to one ofordinary skill in the art to which this invention belongs. It is also tobe understood that the terminology used herein is for the purpose ofdescribing particular embodiments only, and is not intended to limit thescope of the present invention, which will be limited only by theclaims.

It is to be understood that, unless otherwise specifically noted, allpercentages recited in this specification are by weight.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary process for producing a pomegranate extractuseful in the present invention.

FIG. 2 shows the dose dependent reduction in melanin production withpomegranate extract standardized to 20% punicalagin.

FIG. 3 shows that the combination of a pomegranate extract and aSiberian larch extract synergistically reduces the melanin production.

DETAILED DESCRIPTION

The present invention is based on the surprising discovery that apomegranate extract that is standardized to about 20% punicalaginprovides a dose dependent effect on melanin production. As shown in FIG.2, melanin production is increasingly reduced or inhibited with anincrease in the dose of pomegranate extract.

Accordingly, one aspect of the present invention provides a topicalcomposition that includes a pomegranate extract in sufficient amounts toachieve a reduction in melanin production.

Pomegranate Extract

Pomegranates can be extracted to yield an extract of pomegranate(pomegranate extract) that is useful in unique compositions of thepresent invention. When extracted, pomegranate, known as Punicagranatum, is standardized to punicalagin content. For example, thepomegranate extract is standardized to about 20% punicalagin content.Punicalagins exist as isomers of2,3,hexahydroxydiphenoyl-gallagyl-D-glucose. An exemplary structure isshown below:

While it is known that in an acidic environment punicalagin mayhydrolyze to ellagic acid, the compositions in which the pomegranateextract is used have a generally neutral pH. Thus, the pomegranateextract in the compositions of the present invention are not hydrolyzedto ellagic acid. Nevertheless, it has been found that the pomegranateextract that has been standardized to about 20% punicalagin provides adose dependent reduction in melanin production.

Pomegranate extracts may be commercially obtained from various sourcesincluding Nature's Way (Springville, Utah), Nature's Herbs (AmericanFork, Utah), Swansen's Health Products (Fargo, N. Dak.) and Doctor'sTrust Vitamins (Orlando, Fla.). In addition, a suitable pomegranateextract may be obtained using any of the extraction techniques discussedmore fully below or known in the art.

The pomegranate extract useful in the composition of the presentinvention is standardized to about 20% punicalagin. One of skill in theart will appreciate that the extract may be standardized to other levelsof punicalagin. For example, the pomegranate extract could bestandardized to about 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%,75%, 80%, 85%, 90%, or 95% punicalagin content.

The pomegranate extract may be incorporated into the compositions of thepresent invention in an amount from about 0.001% to about 10%, or in anamount from about 0.01% to about 5% when standardized to about 20%punicalagin. Of course, one of skill in the art will appreciate that theamount of the extract incorporated into the composition may depend onthe standardized content of punicalagin. Thus, if the pomegranateextract is standardized to about 40% punicalagin, the above describedamounts of the pomegranate extract will be reduced by one-half, e.g., inan amount from about 0.0005% to about 5%.

Another aspect of the present invention includes combining thepomegranate extract described above with a larix extract (e.g., Larixsibirica, Siberian larch). Surprisingly and unexpectedly it was foundthat the combination provided greater than expected melanin inhibitionand thus an increase in skin whitening or lightening.

Larix Extract

The plant genus Larix refers generally to any of the numerous conifersthat have deciduous needlelike leaves. The Larix genus may include atleast the following species: Larix amabilis, Larix americana, Larixamurensis, Larix cajanderi, Larix czekanowskii, Larix dahurica, Larixdecidua, Larix eurolepis, Larix europaea, Larix gmelinii, Larixgriffithiana, Larix griffithii, Larix himalaica, Larix japonica, Larixkaempferi, Larix kamtschatica, Larix kongboensis, Larix koreana, Larixkurilensis, Larix laricina, Larix leptolepis, Larix lyaffii, Larixmastersiana, Larix occidentalis, Larix olgensis, Larix potaninii, Larixprincipis-rupprechtii, Larix russica, Larix sibirica, Larix speciosa,Larix sukaczewii.

A desirable extract obtained from Larix and, in particular from Larixsibirica (Siberian larch) includes taxifolin. When extracted the Larixextract is standardized to about 80% taxifolin content. Taxifolin (alsoreferred to as dihydroquercetin) has the following structure:

Larix extracts, particularly Siberian larch extracts may be commerciallyobtained from various sources including Lalilab Inc., 1415 Hamin Rd,Durham, N.C. 27704, USA. In addition, a suitable Larix extract may beobtained using any of the extraction techniques discussed more fullybelow or known in the art.

As noted above, the Larix extract is standardized to about 80%taxifolin. One of skill in the art will appreciate that the extract maybe standardized to other levels of taxifolin. For example, the Larixextract could be standardized to about 25%, 30%, 35%, 40%, 45%, 50%,55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, or 95% taxifolin content.

The Larix extract may be incorporated into the composition of thepresent invention in an amount from about 0.001% to about 10%, or in anamount from about 0.01% to about 5%. Of course, one of skill in the artwill appreciate that the amount of the extract incorporated into thecomposition may depend on the standardized content of taxifolin. Thus,if the Larix extract is standardized to about 40% taxifolin, the abovedescribed amounts of the Larix extract will be reduced by one-half,e.g., in an amount from about 0.0005% to about 5%.

Exemplary Extraction Processes

In one example, an extract useful in the unique compositions of thepresent invention might be obtained using an organic solvent extractiontechnique. In another example, solvent sequential fractionation may beused to obtain an extract useful in the unique compositions of thepresent invention. Total hydro-ethanolic extraction techniques mightalso be used to obtain an extract useful in the unique compositions ofthe present invention. Generally, this is referred to as a lump-sumextraction. The extract generated in this process will contain a broadvariety of phytochemicals present in the extracted material includingfat and water solubles. Following collection of the extract solution,the solvent will be evaporated, resulting in the extract.

Total ethanol extraction may also be used in the present invention. Thistechnique uses ethanol, rather than hydro-ethanol, as the solvent. Thisextraction technique generates an extract that may include fat solubleand/or lipophilic compounds in addition to water soluble compounds.

Another example of an extraction technique that might be used to obtainan extract useful in the present invention is supercritical fluid carbondioxide extraction (SFE). In this extraction procedure the material tobe extracted is not exposed to any organic solvents. Rather, theextraction solvent is carbon dioxide, with or without a modifier, insupercritical conditions (>31.3° C. and >73.8 bar). Those of skill inthe art will appreciate that temperature and pressure conditions can bevaried to obtain the best yield of extract. This technique generates anextract of fat soluble and/or lipophilic compounds, similar to the totalhexane and ethyl acetate extraction technique described above.

Those of skill in the art will appreciate that there are many otherextraction processes, both known in the art and described in variouspatents and publications that can be used to obtain the extracts to beused in practicing the present invention. For example, the extractionprocedures described in the following references, which are incorporatedherein by reference, could be used in practicing the present invention:Murga et al., “Extraction of natural complex phenols and tannins fromgrape seeds by using supercritical mixtures of carbon dioxide andalcohol.” J. Agric Food Chem. 2000 August:48(8):3408-12; Hong et al.,“Microwave-assisted extraction of phenolic compounds from grape seed.”Nat Prod Lett. 2001; 15(3):197-204; Ashraf-Khorassani et al.,“Sequential fractionation of grape seeds into oils, polyphenols, andprocyanidins via a single system employing CO₂-based fluids.” J. AgricFood Chem., 2004 May 5; 52(9):2440-4.

According to one example of the present invention, the pomegranateextract is obtained according to the process shown in FIG. 1. In thisprocess, fresh pomegranates are harvested, cut, and milled. Thereafter,the milled pomegranates are extracted with an aqueous ethanol extractantcontaining from about 75 to 80% water and from about 25 to 20% ethanol,with the ratio of the milled pomegranate to extractant in the range fromabout 1:3 to about 1:6.

The product is screened or filtered to create a supernatant and a cake.The cake can be pressed to remove a substantial portion of the liquid,which can be added to the supernatant. The cake can then be dehydratedand used as fiber source. The supernatant may then be distilled toremove the ethanol, which can be recycled as part of the extractant andto form a pomegranate liquid concentrate. The concentrate is dried suchas by spray drying to provide a dried pomegranate extract that can beassayed and standardized to about 20% punicalagin.

Compositions of the Invention

Compositions of the present invention may be formulated in an acceptablecarrier and may be prepared, packaged, and labeled for increasing skinwhitening or lightening, inhibiting or decreasing, or reducingmelanogenisis, melanin, or pigmentation.

In one example, the invention is a composition for increasing skinwhitening or lightening comprising an effective amount of a pomegranateextract to reduce melanin production. The pomegranate extract may bestandardized to about 20% punicalagin. The composition may include acosmetically acceptable vehicle. The composition may have a pH betweenabout 6.0 to about 8.0, or alternatively the composition may have a pHthat is substantially neutral.

In another example the invention is a composition for increasing skinwhitening or lightening comprising a combination of an effective amountof a pomegranate extract and an effective amount of a Siberian larchextract, wherein the combination reduces or inhibits melanin production.The pomegranate extract may be standardized to about 20% punicalagin.The Siberian larch may be standardized to about 80% taxifolin. Thecomposition may include a cosmetically acceptable vehicle. Thecomposition may have a pH between about 6.0 to about 8.0, oralternatively the composition may have a pH that is substantiallyneutral. It is to be understood that the composition may include eachabove alternatives individually, or in one or more combinations.

In another example, the invention is a composition for increasing skinwhitening or lightening comprising a combination of a pomegranateextract and a Siberian larch extract, wherein the combination increasesthe whiteness or lightness of skin and such that the pomegranate extractis standardized to about 20% punicalagin and the Siberian larch isstandardized to about 80% taxifolin.

In another example, the invention is a composition for increasing skinwhitening or lightening comprising a combination of a pomegranateextract and a Siberian larch extract, wherein the combination increasesthe whiteness or lightness of skin and such that the pomegranate extractis present in an amount from about 0.001% to about 10% and the Siberianlarch is present in amount from about 0.001% to about 10%.

In one example, the invention includes a composition containing acombination of a pomegranate extract and a Siberian larch extract whereeach extract is present in a ratio from about 1:2 to about 2:1 and inone example each is present in a ratio of about 1:1.

In a further example, the invention is a method of increasing or skinwhitening or lightening that comprises administering to the subject acomposition that includes a combination of a pomegranate extract and aSiberian larch extract, wherein the combination reduces or decreasesmelanogenisis, pigmentation, or both.

The compositions of the invention may be administered topically. Ingeneral, the combinations of the invention are included in acosmetically acceptable vehicle. Examples of cosmetically acceptablevehicles suitable for all embodiments of the present invention include,but are not limited to, water, glycerin, various alcohols such asethanol, propyl alcohol, vegetable oil, mineral oil, silicone oils,fatty ethers, fatty esters, fatty alcohols, glycols, polyglycols or anycombinations thereof. Methods of formulation are well known in the artand are disclosed, for example, in Remington's Pharmaceutical Sciences,Gennaro, Mack Publishing Co., Easton Pa., 1990, which is incorporatedherein by reference.

The compositions of the present invention may be formulated in anyconvenient form suitable for topical application to the skin. Such formsinclude aerosol spray, gel, cream, dispersion, emulsion, foam, liquid,lotion, mousse, patch, pomade, powder, pump spray, solid, solution,stick or towelette. Suitable emulsions include oil-in-water,water-in-oil, and water-in-silicone emulsions.

The compositions may be administered as needed, daily, several times perday or in any suitable regimen such that the desired outcome isachieved. In the method, the frequency of topical applications willdepend on several factors, including the desired level of suppression ofmelanogenesis. A suitable regimen includes application to the skin twicedaily, with one application in the morning and one in the evening. Theamount of the composition used in each application will also depend onseveral factors, including the desired level of suppression ofmelanogenesis and the content of the extract in the composition.

EXAMPLES Example 1 Pomegranate Extract Standardized to 20% PunicalaginDemonstrated Dose Dependent Reduction of Melanin Production

To determine if the punicalagin present in pomegranate affected melaninproduction, the following assay was performed. Standardized pomegranateextract containing 20% punicalagin was tested. The pomegranate extractin an amount of 20 μg, 60 μg, and 100 μg was solubilized in DMSO andadded to Melan-a cells that were freshly seeded at a density of 5×10⁴cells on a 24 well plate. The cytosolic pH of the Melan-a melanocytes inthis assay is about 6.8 and thus, it is believed that the punicalaginpresent in the tested pomegranate extract does not hydrolyze to ellagicacid. Each dose of the pomegranate extract was added to the cells intriplicate. The final concentration of DMSO in the culture medium wasmaintained at 0.25%. Forty eight hours following the first set oftreatment, the cells were again treated with the pomegranate extract andsupplemented with fresh medium. Two days later, melanin was extractedand quantified by normalizing with protein content, following the methoddescribed by Komatsu et al. (Pigment Cell Res. 2005, 18:447).

Inhibitory activity of samples was reported as % reduction in melaninproduction compared to 100% untreated control (UT). Phenylthiourea (PTU)a well known tyrosinase inhibitor was used as positive inhibitor controlin the assay. FIG. 2 plots the results. It can be seen that the use of apomegranate extract standardized to 20% punicalagin provided a dosedependent reduction in melanin production.

Example 2 Pomegranate Extract and Siberian Larch Synergistically ReduceMelanin Production

To determine the effect of the combination of a pomegranate extract andSiberian larch on melanin production the following assay was conducted.The test compositions listed in Table 1 were solubilized in DMSO andadded to Melan-a cells that were freshly seeded at a density of 5×10⁴cells on a 24 well plate. The cytosolic pH of the Melan-a melanocytes inthis assay is about 6.8 and thus, it is believed that the punicalaginpresent in the tested pomegranate extract does not hydrolyze to ellagicacid. Each dose of the test composition was added to the cells intriplicate. The final concentration of DMSO in the culture medium wasmaintained at 0.25%. Forty eight hours following the first set oftreatment, the cells were again treated with the test composition andsupplemented with fresh medium. Two days later, melanin was extractedand quantified by normalizing with protein content, following the methoddescribed by Komatsu et al. (Pigment Cell Res. 2005, 18:447).

TABLE 1 Test Composition Amount (μg) Phenylthiourea (PTU) 60 SiberianLarch extract (standardized to 50 80% Taxifolin) Siberian Larch extract(standardized to 30 80% Taxifolin) Pomegranate extract (standardized to20% 50 punicalagin) Pomegranate extract (standardized to 20% 25punicalagin) Combination of Siberian Larch extract 25 of Siberian Larch(standardized to 80% Taxifolin) extract and 25 of and Pomegranateextract Pomegranate extract (standardized to 20% punicalagin)Combination of Siberian Larch extract 15 of Siberian Larch (standardizedto 80% Taxifolin) extract and 12 of and Pomegranate extract Pomegranateextract (standardized to 20% punicalagin)

Inhibitory activity of samples was reported as % reduction in melaninproduction compared to 100% untreated control (UT). Phenylthiourea (PTU)a well known tyrosinase inhibitor was used as positive inhibitor controlin the assay. FIG. 3 plots the results. It can be seen that whencompared to Siberian Larch extract standardized to 80% taxifolin andtested at 50 μg/ml and 30 μg/ml alone and to Pomegranate extractstandardized to 20% punicalagin and tested at 50 μg/ml and 25 μg/ml, thecombination of Pomegranate extract and Siberian Larch extract in asubstantially 1:1 ratio to provide a total of 50 μg/ml and 27 μg/ml oftested composition provided a greater than two fold reduction in melaninproduction.

It is intended that the foregoing detailed description be regarded asillustrative rather than limiting, and that it be understood that it isthe following claims, including all equivalents, that are intended todefine the spirit and scope of this invention.

1. A topical composition comprising a cosmetically acceptable vehicleand the combination of a pomegranate extract standardized to 20%punicalagin and present in an amount from about 0.001% to about 10% ofthe composition and a Siberian larch extract standardized to 80%taxifolin and present in an amount from about 0.001% to about 10% of thecomposition, wherein the pomegranate extract and the Siberian larchextract are included in a ratio of about 1.1 and wherein the compositionhas a pH between about 6.0 and 8.0.